This invention relates to an improvement in the operation of strand production machines, such as ring spinning frames.
During the operation of such machines, raw material is converted into continuous strands, such as yarns, and wound up on bobbins or tubes to form packages. The packages are designed to hold a predetermined nominal quantity (by weight or length) of the strand material. When a full package is formed on the machine, the full package is removed from the machine or "doffed" and replaced by an empty tube or bobbin. Although machines have been produced for automating the doffing function on certain strand production machines, it is more common for the doffing function to be carried out by an operator conventionally referred to as a "doffer".
The conventional procedure for doffing the strand processing machines, which has been employed for many years, may be characterized as "cycle doffing". In cycle doffing, each doffer is assigned a group of machines, for example eight machines. The machines are doffed in cycles, with the doff cycle for each machine running a predetermined period of time. The doffer will doff each machine a certain number of times during each shift, depending upon the length of the doff cycle. Ideally, the doff cycles of the respective machines for which the doffer is responsible are staggered so that by the time the doffer has completed one machine, another machine is approaching readiness for doffing. However in actual practice, the doff cycles may not be evenly distributed, and there may thus result periods during which the doffer has idle time. Also, because of uneven distribution of the cycles, there may occur "short doffs" in which a machine is doffed before the packages are filled to the optimum desired amount. Also, under some circumstances, a machine may be ready for doffing while the doffer is still busy tending to another machine, which may result in producing a larger than standard package, which is undesirable, or if the machine is stopped, in nonproductive standing time while the machine awaits a doffer. It will be seen that the above circumstances result in inefficiences in the use of available manpower and in the utilization of the production equipment.
ln an effort to overcome some of the disadvantages and limitations of the aforementioned cycle doffing procedure, it has been proposed to employ a procedure whereby the doffers are not permanently assigned to specified frames, but instead are assigned to a particular frame as the doffer becomes available and a frame becomes ready for doffing. Applicants are aware of at least a couple of instances in textile mills in which this approach has been implemented by using a type of mechanical linkage or switch on the frame, usually on the builder motion, for sensing when the doffing cycle is completed and signalling a computer which makes the frame assignment to the doffer. However, the capabilities of these systems were fairly restricted and did not involve significant frame monitoring functions or data gathering and reporting capabilities, nor did the systems actually exert control over the operation of the frames themselves.
It is an object of the present invention to overcome the aforementioned disadvantages and deficiencies of the conventional "cycle doffing" approach, and to make optimum and most efficient use of available manpower and production equipment resources through the use of an improved "random doffing" approach in which available manpower is dispatched on a priority basis to the individual strand production machines which most require attention. It is a further object of the invention to provide a doff management system in which the production status of each machine is monitored and altered if needed, and changes in production status are recorded to permit producing various historical reports concerning the textile mill operation and its efficiency.